Recently, there have been many traffic accidents on freeways and the like in which a vehicle crashes into another vehicle positioned at the end of traffic congestion, and various countermeasures have been taken. For instance, according to an example of methods for providing drivers of vehicles with information about traffic congestion, which is an example of road conditions, sensors for monitoring traffic congestion and information display boards are provided at a number of places on freeways. An integrated control apparatus judges whether there is traffic congestion based on detection results from the sensors, so that congestion information such as “Congestion Ahead” is displayed on the information display boards.
As a result, the drivers of the vehicles who see the congestion information on the information display boards pay attention and address the situation by, for example, reducing the speed of the vehicle, as necessary.
In addition, according to a conventional technique, a system that provides drivers of vehicles with information about traffic congestion has been put to practical use. In this system, an integrated control apparatus as described above transmits the information about traffic congestion to navigation apparatuses installed on the vehicles via optical/electric wave beacons disposed on the roads or via Frequency Modulation (FM) multiplex broadcasting (see Patent Document 1).
Patent Document 1: Japanese Patent Application Laid-open No. 2004-132737
According to the conventional technique, the integrated control apparatus exercises integrated control by collecting the detection results from the sensors and providing the information about the traffic congestion. Thus, it is necessary to maintain a network for connecting various units to the integrated control apparatus. Consequently, a problem arises where the cost is high.
Also, according to the conventional technique, after the detection results are collected in the integrated control apparatus first, a judgment is made on the condition of traffic congestion, before the information about the road conditions (i.e. the traffic congestion) is displayed on the information display boards. Thus, the processing performed by the integrated control apparatus takes time. Consequently, another problem arises where it is not possible to give information of the road conditions in a real-time manner.
In view of the problems explained above, it is an object of the present invention to provide a road-condition informing apparatus and a road-condition informing method with a capability of informing road conditions in real time at a low cost.